Help with a solution for a two wire AC system

Hi Everyone.

I have been working on setting up smart thermostats and smart AC control in my place. I have stumbled on a really hard problem, and I would really appreciate if you all would be so kind to offer me some guidance!

I have a Daikin cassette Air conditoner (daikin brc1c62) with a hard wired remote controller (pictured below). What this means is that the AC unit itself is controlled by this device that is mounted on the wall. The problem is when I removed this thermostat / remote controller, I realized there were only two wires connected to it, to poles P1 and P2 on the back of the controller.

I tried using a Go Control Zwave thermostat to replace it, but the problem is, regular smart thermostats use 4 or 5 wires.
I also have a Sensibo sky connected to a different split AC unit that works with an IR remote but there is no IR remote with the Daikin system to use with a Sensibo.
I also encountered this problem with another AC system (toshiba rbc-amt31e) that also uses this two wire system to connect the AC directly to a wall mounted remote controller.

Does anyone have any solution that I may use? Maybe there is some form of adapter or wiring?
I spoke to a Daikin rep and he told me that someone was able to connect their AC system similar to mine to a smart thermostat but he wasn’t entirely sure how.

Thanks for any help!

Maybe it can be setup to always be on after power loss?..

If so, then you can forget the Smart therm and just use a Smart Plug or Relay? Then setup a temp sensor to turn on and off…

Just an idea.

Not sure if this will help but I had a Carrier system that only had two wires. I found that the unit did support the typical five wires but instead ran those wires to a small control unit, then two wires to my thermostat. I disconnected the thermostat and the control unit and was able to connect an Ecobee thermostat.

There’s a lot to dislike about Daikin (Korean) equipment - the wall controller is just a tiny piece of hate. You won’t be able to do automation with that controller.

You could replace your wired controller with wireless (# BRC7E618 ) and try the Sensibo - I’m not familiar.

The “Cassette” unit, I call it the “indoor unit”, may have jumpered terminals T1+T2 for remote enable/disable - that’s all the automation you can do. When enabled, I assume it operates with the heating/cooling setpoints in the wall controller.

Lookup the capabilities by the model of the indoor unit.

You can use your Go Control thermostat and use the Venstar Add a Wire to convert your 2 to 3 wire and it should work with the CT-xx/GoControl thermostats.

See this post:

Add the wireless remote kit? It comes with a receiver that plugs into the IDU. You need to check your model but if you are using that BRC controller chances are it will work.

Daikin is Japanese. LG and Samsung are Korean. Get it right.

Most mini split sytems are 2 wire. Show me a ductless unit that isn’t and it will be 3 wire. 4 wire is common in residential splits.

Following… I know its been a year, same situation here with a newer model though same style wired controller… Did you figure this out? Specially with voice activation like Alexa?

The P1/P2 bus is a Daikin proprietary 2-wire control bus. It is based on the Japanese Home Bus System. You can read the data on the bus, and then try to understand the packet format. On github there is more information, together with the schematics and some code for reading (and writing) bytes from (and to) the P1/P2 bus: